linux-kernel - Re: [PATCH v2 5/5] ARM: shmobile: lager: (DEVEL) add CPUFreq support

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Date:	Fri, 27 Sep 2013 10:37:37 +0200 (CEST)
From:	Guennadi Liakhovetski <g.liakhovetski@....de>
To:	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
cc:	linux-kernel@...r.kernel.org, Magnus Damm <magnus.damm@...il.com>,
	linux-sh@...r.kernel.org, Linus Walleij <linus.walleij@...aro.org>,
	Laurent Pinchart <laurent.pinchart@...asonboard.com>,
	Simon Horman <horms@...ge.net.au>
Subject: Re: [PATCH v2 5/5] ARM: shmobile: lager: (DEVEL) add CPUFreq support

Hi Sergei

On Thu, 26 Sep 2013, Sergei Shtylyov wrote:

> Hello.
> 
> On 09/26/2013 09:21 PM, Guennadi Liakhovetski wrote:
> 
> > The Lager board uses a DA9210 voltage regulator to supply DVFS power to the
> > CA15 cores on the r8a7790 SoC. This patch adds CPUFreq support for that
> > board using the cpufreq-cpu0 driver.
> 
> > Signed-off-by: Guennadi Liakhovetski <g.liakhovetski+renesas@...il.com>
> > ---
> 
> > v2: added 'status = "okay";' to the i2c bus
> 
> >   arch/arm/boot/dts/r8a7790-lager-reference.dts  |   33
> > ++++++++++++++++++++++++
> >   arch/arm/mach-shmobile/board-lager-reference.c |    4 ++-
> >   2 files changed, 36 insertions(+), 1 deletions(-)
> 
> > diff --git a/arch/arm/boot/dts/r8a7790-lager-reference.dts
> > b/arch/arm/boot/dts/r8a7790-lager-reference.dts
> > index c462ef1..1ce0a97 100644
> > --- a/arch/arm/boot/dts/r8a7790-lager-reference.dts
> > +++ b/arch/arm/boot/dts/r8a7790-lager-reference.dts
> > @@ -43,3 +43,36 @@
> >   		};
> >   	};
> >   };
> > +
> > +&i2c3 {
> > +	status = "okay";
> > +	pinctrl-names = "default";
> > +	pinctrl-0 = <&i2c3_pins>;
> > +
> > +	vdd_dvfs: da9210@68 {
> 
>   ePAPR spec [1] says: "The name of a node should be somewhat generic,
> reflecting the function of the device and not its precise programming model."

Sure, but I think it is common in Linux .dts files for I2C devices to use 
"<model>@<i2c addr>" as a name.

> So I suggest "regulator" instead of "da9210".
> 
> > +		compatible = "diasemi,da9210";
> > +		reg = <0x68>;
> > +
> > +		regulator-min-microvolt = <900000>;
> > +		regulator-max-microvolt = <1000000>;
> > +		regulator-boot-on;
> > +		regulator-always-on;
> > +	};
> > +};
> [...]
> > diff --git a/arch/arm/mach-shmobile/board-lager-reference.c
> > b/arch/arm/mach-shmobile/board-lager-reference.c
> > index 1a1a4a8..2bc8bae 100644
> > --- a/arch/arm/mach-shmobile/board-lager-reference.c
> > +++ b/arch/arm/mach-shmobile/board-lager-reference.c
> [...]
> > @@ -29,7 +30,8 @@ static void __init lager_add_standard_devices(void)
> >   	r8a7790_clock_init();
> > 
> >   	r8a7790_add_dt_devices();
> > -        of_platform_populate(NULL, of_default_bus_match_table, NULL, NULL);
> > +	of_platform_populate(NULL, of_default_bus_match_table, NULL, NULL);
> 
>    Hm, "drove-by" cleanup?

This should be avoided in general, but this kind of stuff really doesn't 
deserve neither a separate patch nor a mention. Don't waste your precious 
brain cycles.

> > +	platform_device_register_simple("cpufreq-cpu0", -1, NULL, 0);
> >   }
> > 
> >   static const char *lager_boards_compat_dt[] __initdata = {
> 
>    Shouldn't the patch be split into .dts and .c parts, I wonder?

Simon didn't complain, but perhaps it should, yes. I think I'll resubmit 
this as 2 patches with no changes.

Thanks
Guennadi

> [1] http://www.power.org/resources/downloads/Power_ePAPR_APPROVED_v1.0.pdf
> 
> WBR, Sergei

---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/
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